How does Preigntion Adder Lambda and Cyl Press Lambda Modifier work?

[GrannySShifting]

Say your Preign Limit was 29 degrees at current load/rpm - is it commanded or actual lambda being reference in the Adder and Modifier tables?

Lets say its .80 Lambda and value is -1.3 does that mean Preignition limit is 30.3 degrees or 27.7 degrees now or something else?

For Cyl Press Limit say its 31 degrees and Lambda Modifier at the lambda is 3, does that make Cyl Press Limit 34 or 28 now?

[Thatwhite5.0]

Honestly, Cylinder pressure and pre ignition tables get maxed out 63.5 on every car, ever mod.


The modifier is added to the limit table. If the limit was 29* and the lambda modifier was -1.3, the limit would be 27.7.

The lambda modifier at 3 would be 32.

[GrannySShifting]

Honestly, Cylinder pressure and pre ignition tables get maxed out 63.5 on every car, ever mod.


The modifier is added to the limit table. If the limit was 29* and the lambda modifier was -1.3, the limit would be 27.7.

The lambda modifier at 3 would be 32.

Thats exactly how I thought it would work just wanted to make sure.

This car was creeping timing up and I couldnt find table it was getting that high from so i temp used one of these to limit it in that spot, otherwise I trust my tunign instincts I generally want it to do exactly what I tell it to do period, nothing more

Id would zero out both modifiers even if I would use the limit tables - no reason to have that many layers. GM is good for doing that kinda stuff too

[skythunder83]

Talking on that, I have had long big challenge with random misfire counting at idle and while driving, it's GEN2 2017 GT NA, did everything, smoke test, changed MAF, injectors, checked fuel pressure, new spark plug set well gapped and new coils, I have no DTC at all other than P0300 and based on long drive I see some related to cylinder number. Engine was pressure tested as well and it was very well (25K mile only), not much mods but CAI and long exhaust, when it idle I can see random count of misfire from different cylinders with no pattern, finally I did 0 the Preignition at 0.3 load and 1000 RPM then I have no more misfire at all. I know that this map started on GEN 2 not before, but why it was causing my car random misfiring?